As to a control panel responsible for instrumentation and control of a plant, transition from a conventional analog-control-type control panel to a digital-control-type control panel has been recently progressing from the viewpoint of reliability and maintainability. Therefore, in an existing plant, a task of replacing an existing analog-control-type control panel with another digital-control-type control panel has been performed.
Generally, in the task of replacing an existing control panel with another control panel, a cable disposed between a control target device and the existing control panel is first removed from the control panel, with the operation of a plant stopped. Thereafter, when the control panel is removed and another control panel is placed, the removed cable is connected to this newly-provided control panel. Then, a trial run of the newly-provided control panel is conducted to perform wiring check and the like. If it is confirmed that there is nothing wrong, the replacement task is ended.
As described above, the task of replacing the control panel involves the stop of the operation of the plant, and thus, the replacement task is normally performed during a maintenance and inspection period of the plant. In order to increase an operation rate of the plant, completion of the replacement task within the maintenance and inspection period is necessary.
As a method of replacing a control panel, Japanese Patent Laying-Open No. 2008-289280 (PTD 1), for example, discloses a method of switching an existing wiring connected to a control apparatus of an existing control panel via a card-side terminal block to a control apparatus of a newly-provided control panel, thereby replacing the control panel. According to the replacement method described in PTD 1, a relay frame, which incorporates therein card-side terminal receptacles corresponding to the card-side terminal block and relay terminals connected to terminals of the card-side terminal receptacles, is mounted at a prescribed position of the existing control panel in operation. Next, during operation of the existing control panel, an extension cable is connected between the relay terminals in the relay frame and the control apparatus of the newly-provided control panel. Thereafter, the existing control panel is stopped, and then, the card-side terminal block is removed from the control apparatus of the existing control panel and connected to the card-side terminal receptacles in the relay frame.